Work on the isolation, characterization and quantitation of Agrobacterium tumefaciens specific DNA, RNA, and products from crown gall tumor cells is being continued. DNA and RNA of high specific radioactivity are used as molecular probes in examining the type of nucleic acids in cells at early and late phases of tumor transformation. Also, the possibility of abnormal nucleic acid metabolism is being studied with emphasis on DNA- and RNA-polymerizing enzymes. Experiments on the modulation of cyclic nucleotides are also underway in view of the potent cyclic phosphodiesterase inhibitor in crown gall tumor cells.